class_docstr: This class has pool interface but performs all work in calls to get_results. It is sometimes convenient
  to substitute a real pool with this dummy implementation.
  
  Found this class useful when profiling worker code. When on a separate thread, the worker code was not observable
  (out of the box) by the profiler
code: def start(self, worker_class, worker_args=None, ventilator=None):
      # Instantiate a single worker with all the args
      self._worker = worker_class(
          0, self._results_queue.append, worker_args
      )
  
      if ventilator:
          self._ventilator = ventilator
          self._ventilator.start()
  
file_path: petastorm/petastorm/workers_pool/dummy_pool.py
imports: from time import sleep
  from petastorm.workers_pool import EmptyResultError
label_desc: Use image node_id 2 for calling the DummyPool obj's underlying member method code with example usage: obj.start(worker_class, worker_args, ventilator) without return types